WO2013061307A1

WO2013061307A1 - A connecting group for a filtering cartridge.

Info

Publication number: WO2013061307A1
Application number: PCT/IB2012/055965
Authority: WO
Inventors: Albrigi MASSIMO
Original assignee: Alteco S.R.L.
Priority date: 2011-10-28
Filing date: 2012-10-29
Publication date: 2013-05-02
Also published as: ITVR20110199A1

Abstract

The present invention relates to a connecting group for a filtering unit (2) for filtering a fluid, comprising an annular socket member (3) integral with, or connectable to the filtering unit (2), and delimiting an inner through passage (1 1 ), a base member (4) formed with a through opening (13) in fluid communication, in use, with the through passage (1 1 ), and sealing means (7, 8; 7a; 70, 80) between the socket member (3) and the base member (4), the socket member (3) and the base member (4) delimiting, in use, an inner surface (5) designed to enter in contact either with a filtered fluid or a fluid to be filtered by the filtering unit (2), and an outer surface (6) designed to enter in contact with fluid to be filtered, or filtered fluid, respectively, by the filtering unit (2), the sealing means having a first part or component (7, 7a, 70) designed to seal the connecting group at the outer surface (6) and a second part or component (8, 7a, 80) designed to seal the connecting group at the inner surface (5).

Description

A CONNECTING GROUP FOR A FILTERING CARTRIDGE.

The present invention regards a connecting group for a filtering unit, e. g. a filtering cartridge, particularly suitable for cartridges for sterile filtration, nanofiltration, osmosis, microfiltration and ultrafiltration of fluids or for any non- aseptic technical fields, such as non-aseptic industrial, chemical, and petrochemical fields.

As known, in the sterile microfiltration and ultrafiltration field various types of connecting groups for connecting one end of filtering elements or cartridges to a receiving seat have been proposed up to now. Such groups are designed to suitably locate a filtering cartridge in its receiving seat in order to keep it in a standing working position in use, but are normally so structured as to delimit a number of stagnation zones and/or retention meanders for the fluid to be filtered. A typical connecting group includes a bayonet-type connecting means.

In general, connecting groups must ensure both proper stability for the filtering cartridge and sealing against the different pressures in the various zones or spaces containing fluid to be filtered and filtered fluid. Usually, such zones are separated by a membrane being a component of the filtering unit.

The German Utility Model DE-20 2007008473 U 1 discloses a filtering unit having a main side wall enclosing a filtering cartridge and delimiting therewith an annular chamber for the flow of a fluid to be filtered. The filtering unit has a fluid inlet in fluid communication with the annular chamber, and an outlet in fluid communication with the outlet end of the filtering cartridge. The fluid inlet and outlet are both located at the same end of the cartridge, and separated from one another by an inner tubular wall extending from the base of the cartridge element up to the inlet end thereof. Thus, the inlet (delimited between the main side wall and the internal tubular wall) is ring-shaped and external to, and coaxial with, an inner circular outlet (delimited by the inner tubular wall). Owing to such a structure, fluid to be filtered enters at the inlet end, flows into the annular chamber, then crosses the cartridge membrane and is discharged at the outlet.

The filtering unit further comprises bayonet-type connecting means provided at the inlet end on the internal side of main side wall, and one gasket mounted on the inner side of the main side wall opposite to the inlet end with respect to the connecting means.

Upon assembling, such a filtering unit cannot be suitably sanitized, since it delimits stagnation zones particularly at the bayonet type connecting means, that are not adequately tight sealed from the flow of the fluid to be filtered. Moreover, the gasket can be cleaned only after dismounting the filtering unit.

Thus, the need is felt for a connecting group for a filtration cartridge, which can be easily cleaned, is self-drainable, and has no "dead zones" where bacterial or polluting loads can stagnate or proliferate, as is the case with the filtration of milk in the foodstuff field or in other industrial fields, such as the paint field, where cartridges for sterile microfiltration or ultrafiltration are used.

The main object of the present invention is to provide a connecting group for a filtering cartridge, which can be protected against stagnation or proliferation of bacteria or other polluting loads.

Another object of the present invention is to provide a connecting group for a filtering cartridge, which can be cleaned and is self-drainable.

Another object of the present invention is to provide a connecting group for a filtering cartridge that can be easily and rapidly sanitized. Another object of the present invention is to provide a connecting group as indicated above, which is suitable for being used for fluid sterile filtration, nanofiltration, osmosis, microfiltration or ultrafiltration in any industrial field, such as the foodstuff field, e. g. filtering milk, and for any non-aseptic technical fields, such as non-aseptic industrial, chemical, and petrochemical fields.

Another object of the present invention is to provide a connecting group suitable for providing a filtering cartridge or unit with a seal for the differential pressures between a space containing fluid to be filtered and that for filtered fluid.

Another object of the present invention is to provide a connecting group for a filtering cartridge or unit including gasket members with surfaces designed to contact fluid to be filtered or filtered fluid, such surfaces being cleanable without the need of dismounting or disassembling the respective filtering cartridge or unit.

Another object of the present invention is to provide a connecting group meeting the law requirements, particularly in so far as compression and compressed shape of the gaskets are concerned.

According to a first aspect of the present invention, a connecting group is provided for a filtering unit for filtering a fluid, comprising an annular socket member integral with, or connectable to the filtering unit, and delimiting an inner through passage, a base member formed with a through opening in fluid communication, in use, with the through passage, and sealing means between the socket member and the base member,

the socket member and the base member delimiting, in use, an inner surface designed to enter in contact either with a filtered fluid or a fluid to be filtered by the filtering unit, and an outer surface designed to enter in contact with fluid to be filtered, or filtered fluid, respectively, by the filtering unit, the sealing means having a first part or component designed to seal the connecting group at the outer surface and a second part or component designed to seal the connecting group at the inner surface.

Preferably, the socket member has frontal engaging means arranged outside and about the through passage and designed to face, in use, the base member, and

the base member has counter-engaging means arranged outside and about the through opening and designed to engage with the frontal engaging means of the socket member.

Preferably, the first part or component and the second part or component of the sealing means comprises each at least one respective gasket member located in a respective seat formed either in the socket member or in the base member, or formed partly in the socket member and partly in the base member.

Advantageously, a connecting group according to the present invention, have engaging means extending from a surface or being formed in a surface of the socket member contacting, in use, a substantially flat surface of the base member, whereas the counter-engaging means extends from or are formed in the substantially flat surface of the base member designed to abut against the socket member.

Preferably, the socket member has engaging means, whereas the base member has counter-engaging means designed to engage with the engaging means of the socket member, the sealing means being designed to seal, in use, the engaging means and the counter-engaging means.

Advantageously, the connecting group can be provided with a filtering unit secured or integral with the socket member. More advantageously, the filtering unit delimits an internal space in fluid communication with the through opening delimited by the base member.

Further aspects and advantages of the present invention will be clearer from the following detailed description of specific embodiments of connecting groups and filtering units, the description being made with reference to the accompanying drawings, in which:

- Figure 1 is a side elevation view of a filtering cartridge or unit according to the state of art;

- Figure 2 is a exploded view of some components of the filtering unit of Figure 1 ;

- Figure 3 shows a detail on an enlarged scale of Fig. 1 ;

- Figure 4 is a view similar to Figure 3 of another prior art solution;

- Figure 5 is a cross-sectional view of a connection group according to the present invention including a filtering cartridge;

- Figures 6 to 10 are a perspective view from below, a perspective view slightly from above, a plan view, a side view, and a cross-sectional view, respectively, of a socket element of the connecting group of Fig. 1 ;

- Figures 1 1 to 13 are two perspective views slightly from above, and a side view, respectively, of an engagement member of the connecting group of Fig. 1 ;

- Figure 14 is a side view of the engagement member of Figures 1 1 to 13 while being engaged by a socket element;

- Figure 15 is a cross-sectional view of a connecting group according to another embodiment of the present invention without filtering cartridge;

- Figures 16, 17 and 18 are two perspective views, and a side view, respectively, of the engagement member of the connecting group of Figure 15; - Figure 19 is a side view of the engagement member of Figures 1 1 to 13 while being engaged by a socket element;

- Figure 20 is a cross-sectional view of a connecting group according to another embodiment of the present invention without filtering cartridge;

- Figures 21 and 22 are perspective views of an engagement member of the connecting group of Fig. 20;

- Figure 23 shows a plant view of a sealing gasket of the connecting group of Fig. 20;

- Figure 24 is a cross-sectional view of a connecting group according to another embodiment of the present invention without filtering cartridge; and

- Figures 25 to 29 are cross-sectional views of a respective connecting group according various embodiments of the present invention.

In the drawings, equivalent or similar parts or components have been marked with the same reference numerals.

First, with reference to Figures 1 to 3, a prior art solution of a filtering cartridge A fixed to a base member B is shown. The filtering cartridge A comprises a tang portion having a section C designed to be inserted in a bore D formed in the base member B. Moreover, two O-rings E and a flange element F, designed to abut against the base member B, are provided at the tang portion. The filtering cartridge A is kept in position also by means of a tie rod G fixed on the one side, to the top of the filtering cartridge A, and, on the other, to the base member B.

According to another prior art solution shown in Fig. 4, instead of the flange element F, a number of angularly spaced wings or protrusions H extend from the tang portion that are designed to engage in a bayonet fashion the base member B.

With the above prior art solutions, after assembling the filtering unit, a number of fluid stagnation zones between the O-rings E and the flange element F or the wings H and the base member B are delimited. Thus, the prior art filtering units according to Figures 1 to 4 suffer from the above indicated drawbacks the present invention aims at solving.

With reference to the embodiment shown in Figures 5 to 14, a connecting group 1 according to the present invention for a filtration unit, such as a cartridge 2 particularly suitable for sterile filtration, nanofiltration, osmosis, microfiltration and ultrafiltration of fluids or for any non-aseptic technical fields, such as non- aseptic industrial, chemical, and petrochemical fields, is disclosed, which comprises an annular socket member or element 3 integral with, or connectable, e. g. screwable or boltable, to the filtering cartridge 2, and a base member or element 4 acting as a support component for the filtering unit or cartridge 2. The socket member 3 and the base member 4 are engaged, in use, with one another (as also further described hereinbelow), so as to delimit an inner surface 5 designed to be or enter in contact with a filtered fluid or a fluid to be filtered (this depending upon the flow direction during a fluid filtration process) by the filtration unit 2, and an outer surface 6 designed to enter or be in contact with the fluid to be filtered or filtered, respectively, by the filtration unit 2. The socket member 3 can be made of a polymeric plastics, metal, ceramic and the like material.

More particularly, should the socket member 3 be made of polymeric material, it can be provided with a metal reinforcing core or with a core made of a more rigid material than the polymeric material, so as to ensure a suitable pre- load of the gasket members, after the connecting group has been assembled. As will be discussed hereinbelow, a suitable pre-load is important to prevent any fluid by-pass or escape through the connecting group from the zone of the fluid to be filtered to the zone of the filtered fluid.

Preferably, the connecting group comprises sealing means having a first part or component 7 designed to seal the connecting group at the outer surface 6 and a second component 8 designed to seal the connecting group at the inner surface 5.

Particularly referring to embodiment shown in Figures 5 to 14, the connecting group 1 further comprises sealing means having a first gasket or O- ring component or member 7 designed to provide sealing between the outer surface 6 of the socket member 3 and the base member 4, and a second gasket or O-ring component or member 8 designed to provide sealing between the inner surface 5 of the socket member and the base member. The O-rings 7 and 8 are located in respective receiving seats 9 and 10 formed in the socket member 3 (Fig. 10). The gaskets or O-rings 7 and 8 can be made of any suitable material, such as an elastomeric material.

Preferably, the sealing means comprises at least two gasket members 7, 8 located in respective seats 9, 10 formed either in the socket member 3 or in the base member 4. More preferably, the seats 9, 10 are formed either at the edge of the socket member 3 designed to abut, in use, against the base member 4, or at the edge of the through opening 13 in the base member 4 abutting, in use, against the socket element 3.

As it will be understood, the sealing means could include one or more respective O-ring or gasket members 7 at the outer surface 6, and one or more respective O-ring or gasket members 8 at the inner portion 5, although, as will be described hereinbelow, a sole O-ring or gasket member can also be provided (see in particular Fig. 20).

Advantageously, the socket member 3 is a ring with an axis of symmetry x- x delimiting an inner through passage or hole 1 1 through which filtered fluid or fluid to be filtered can flow. In this case, the socket member 3 has an inner cylindrical wall 5 and an outer cylindrical wall 6.

The socket member 3 is preferably formed with one or more angularly spaced recesses 16, arranged outside the through passage 1 1 and each designed to be engaged by a respective protruding or projection extension or member 14 extending from the base member 4. Preferably, the angularly spaced recesses 16 are frontal, i. e. they have an opening facing the base member 4, and extend (inwards the socket member 3) from the surface 3a of the socket member 3 contacting, in use, the base member 4 or a substantially flat surface 4a thereof.

Preferably, one annular recess 16 is provided extending coaxially about the through passage 1 1.

Advantageously, the recesses are provided in an intermediate part of the socket element 3 between the inner surface 5 and the outer surface 6.

Moreover, the socket member 3 is provided with engaging means, whereas the base member has counter-engaging means designed to engage with the engaging means of the socket member 3, the sealing means being designed to seal, in use, the engaging means and the counter-engaging means.

The engaging and the counter-engaging means can be of the bayonet or threaded or snap-fitting or magnetic type. Preferably, the socket member 3 is provided with frontal engaging means in the recess 16, which are arranged to engage, preferably releasably engage, with the counter-engaging means of the base member 4, in the protruding member 14. The frontal engaging means of the socket member 3 are designed to face, in use, the base member 4. Thus, the socket member 3 can be connected to the base member 4 in such a way as to extend entirely outside the opening 13 formed in the base member 4 and about it.

Preferably, the engaging means and the counter-engaging means are designed to removably engage with one another.

The base member 4 is preferably a plate-like member in which a through bore or opening 13 is formed in fluid communication with the through passage 1 1 in the socket element 3, and preferably co-axial, in use, with, and having the same size (diameter) as the through passage 1 1 in the socket member 3. Around the bore 13 a protruding extension 14 is provided, which is an annular element integral with or secured, e. g. by gluing or welding, to the plate-like member 4 and formed with a number of angularly spaced notches each delimiting a transverse receiving seat 15a and a respective hook portion 15b, which are preferably slightly flexible. The protruding extension 14 extends, preferably, from a substantially flat surface 4a of the base member 4 designed to abut against the socket member 3.

More preferably, the protruding member 14 is ring-shaped, in such a way as to enclose the passage 1 1 or opening 13 formed in the respective socket or base member and being substantially coaxial therewith.

The socket member 3 has one or more angularly spaced lugs or lug members 17 provided inside the annular recess/recesses 16, which are equal in number to the receiving seats 15a in the protruding extension 14 and suitable for shape-engaging with a respective hook portion 15b. According to the embodiment shown, the engaging means comprises the recess 16, optionally with lugs 17, whereas the counter-engaging means comprises the protruding extension 14, optionally with the hook portions 15b. Thus, the engaging means are arranged outside and about the through passage 1 1 , whereas the counter- engaging means are arranged outside and about the through opening 13 and designed to engage with the frontal engaging means of the socket member 3.

Upon assembling, the recess 16 of the socket member 3 is inserted onto the protruding extension 14 in such a manner that each lug 17 in the recess(es) 16 enters a respective receiving seat 15a in the protruding extension 14. The socket member 3 is then angularly moved in order to cause the lugs 17 to slide along their respective receiving seats 15a to become engaged by a respective hook portion 15b to establish a bayonet-like engagement therewith.

Preferably, each receiving seat 15a is so shaped as to have an abutment edge 19 for a lug 17 along which the lug is caused to slide. Optionally, the edge 19 has a descending inclined section 19a to assist the insertion of a lug 17 into the seat 15a and an inclined plane step 19b designed to keep the lug 17 in work position in the seat, i. e. to resist backward movements of the lug once it has reached its work position underneath its respective hook portion 15b (Fig. 14).

The annular seats 9 and 10 for gaskets 7 and 8 are preferably formed at the front (inner and outer) edges of the socket member 3, i. e. facing, in use, the base member 4. As an alternative, the seats 9 and 10 are formed partly on the socket member 3 and partly on the base member 4 or entirely on the base member 4, i. e. at the surface of the base member 4 facing and at the socket member 3. Preferably, the gasket member/s is/are located and compressed between the socket member 3 and the base member 4.

A filtering element or unit 2, such as a cylindrical cartridge with a filtering side wall 20, is secured to the socket member 3 in any suitable manner, e. g. by gluing, welding, screwing, or by magnetic anchoring means and delimits an internal space 22 in fluid communication, in use, with the through passage 1 1 and thus with the bore 13 in the base member 4. Preferably, the space 22 is axially aligned and has the same diameter or the same light as the through hole 1 1 and the bore 13.

With reference to the non-limiting embodiment shown on Figure 5, the filtering unit 2, for example, can include a bottom surface 18a, a top surface or member 18b, and a filtration member anchored between the bottom surface 18a and the top surface or member 18b. The filtration member can include a membrane, a grid, a net, sieves or the like designed to filter a fluid passing therethrough, and can be enclosed between the external side wall 20 and an internal wall 21 , the internal wall 21 delimiting the internal space or chamber 22. Of course, the filtering unit can be located in an inverted trim, i. e. with connecting group on the top and filtering unit connected to the bottom surface thereof.

The anchoring means of the connecting group to the filtering unit should ensure the hydraulic seal, and to this regard the connection of such unit could be rigid or flexible, in the second case (flexible anchoring) the filtering unit could flex while being used, without affecting the hydraulic seal.

With the above described connecting group structure, a fluid to be filtered is supplied in any suitable manner to the opening, hole or bore 13 of the base member 4, enters the hole or passage 1 1 and the space 22 of the filtering element 2, flows throughout the filtration member and is discharged outside the filtering unit 2. Alternatively, the fluid to be filtered is supplied to the suitably enclosed zone outside the filtering unit 2, flows throughout the filtration member, enters the inner space 22 of the filtering element 2, and is then discharged through the passage 1 1 and the bore 13.

Upon assembling the socket member 3 onto the base member 4, each lug 17 is slightly deformed in that its tip 17a is forced by the operator to slide underneath its respective hook element 15b, and this will result in the gasket members 7 and 8 being suitably compressed in working conditions. Thus, each receiving seat 15a also acts as cam for the lugs or wings 17 of the socket member.

More particularly, for assembling the socket and base members having the specific protruding extension and recess of Figure 14, first of all the socket element 3 is located with its hole 1 1 substantially aligned with the hole 13 of the base member 2, and then they (socket and base members) are moved closer up to take each lug 17 to abut against the descending inclined section 19a. At this point, the socket and base members are rotated one with respect to other about a longitudinal axis x-x of the holes 1 1 and 13, thereby forcing each lug 17 to slide along the respective seat 15a. Owing to the shape of the descending inclined section 19a, during the approaching step, each lug 17 is deformed in such a way that the tip 17a thereof, i. e. the end of the lug 17 to be first inserted into the seat 15a, is crushed towards the lower edge of the descending inclined section 19a, and subsequently, upon mutually rotating socket and base members, the crushed lug 17 is caused to enter underneath the hook portion 15b, and after the lug 17 is entirely received under the hook portion 15b, it recovers its original shape. Owing to such a structure, the operator entrusted to assemble the filtering unit, during the assembling step, and more particularly during the mutually approaching and rotation steps of the socket and base members, feels it natural to and must push the socket member relatively to the base member, and this will result in the required compression of the gasket members. Therefore, the seats 15a act as cam elements for the lugs or wings of the socket member.

Therefore, the anchoring displacement of the socket and base members can include a general helical path, comprising a first descending or approaching section providing the required compression of the gasket members suitable for providing the required hydraulic seal, and a rotational section, which ensures that the required compression and position of the components of the connection group are maintained.

The socket member 3 and the base member 4 can be easily disassembled by repeating the above-described assembling steps, but in reverse order.

Figures 15 to 19 illustrate another embodiment of connecting group 1 according to the present invention, which is similar to that described above in connection with Figures 5 to 14, but has an ascendant inclined section 19c instead of a descendent section 19a.

During assembling, owing to the presence of the ascendant section 19c, each lug 17 is not deformed when its tip 17a engages its hook element 15b, but only when fully pushed beyond the inclined plane step 19b.

The assembling method of the socket and base members having the specific structure of Figure 19 is similar to the method described with reference to Figure 14, but owing to the shape of the ascendant section 19c, during the approaching step of socket and base members, each lug 17 is not deformed, and subsequently, upon mutually rotating socket and base members, the lug 17 is caused to crush by the hook portion 15b, and after wholly entering the zone underneath the hook portion 15b, the lug 17 recovers its original shape. Owing to such a structure, when the lug 17 is crushed by the hook portion 15b, the required compression of the gasket members 7 is caused, which determines a relative compression of socket and base member, which ensures the hydraulic seal of the gasket member/s.

Figures 20 to 23 show a connecting group 1 , in which the sealing means comprises one annular gasket member 7a substantially co-extensive and, optionally coaxial with the front (i. e. the surface contacting or facing towards the base member 4) of the socket member 3 and designed to be located between the socket member 3 and the base member 4. Thus, the gasket member 7a is designed to separate, in use, the socket member 3 from the base member 4.

Preferably, each gasket or gasket member 7a is formed with a number (four in the Figures) of through openings 7b for letting respective protruding extensions 14 extending from the base member 4 to pass through to enter the frontal recess(es) 16 in the socket member 3. In such case, the gasket 7a comprises a first outer part or component designed to seal the connecting group at the outer surface 6 and a second inner part or component designed to seal the connecting group at the inner surface 5.

Thus, it is evident that a connecting group according to the present invention can include one or more gaskets and one or more protruding extensions and/or recesses.

The embodiment of connecting group according to the present invention shown in Figure 24 includes one or more protective layers 28a, 28b, e. g. of a polymeric material, covering the outer surface and/or the inner surface (i. e. the surface delimiting the bore 13) of the base member 4, i. e. the surfaces of the base member 4 designed to contact fluid filtered and fluid to be filtered.

Such a connecting group can be used for filtering aggressive fluids that would attack the metal components, e. g. made of stainless steel, of the connecting group. However, since the portions of the connecting group including the engaging and counter-engaging means are sealed by the sealing gaskets 7 8, there is no need to provide a protective layer for them.

With the prior art solutions, it is impossible to suitably protect the connecting group from chemical attack by aggressive fluids, and thus prior art connecting groups cannot be used for the treatment (filtration) of aggressive fluids.

Figure 25 shows a connecting group 1 according to the present invention, in which O-rings are replaced by gaskets 70, 80 being square in cross section and seated in respective receiving seats 9a, 10a with sharp edges in the socket 3 or base 4 members.

With reference to Figures 26 to 30, further embodiments of respective connecting groups according to the present invention are shown, which are similar to the embodiment shown in Figures 5 to 14, except that:

- the embodiment shown in Figure 26 has engaging and counter-engaging means including threaded means 24-25; for example, the threaded engaging means extends from a recess in the socket member 3 or from a protruding member integral or connected to the socket member 3, whereas the threaded counter-engaging means extends from a protruding member 14 integral or connected to the base member 4 or from a recess formed in the base member 4; - the embodiment shown on Figure 27 has engaging and counter-engaging means as in the embodiment of Figures 5 to 14, although the socket member 3 has a frontal protruding extension 14 extending from it and the base member 4 is formed with a recess 16 and lug 17 designed to be engaged by the protruding extension 14;

- the embodiment shown on Figure 28 has snap engaging and counter- engaging means 26-27, which could also provide a not releasable engagement;

- in the embodiment shown on Figure 29 both the socket member 3 and the base member 4 have each a protruding extension 14 and a recess 16 extending coaxially to the passage 1 1 and the bore 13, respectively, designed to be engaged by a respective recess and protruding extension; and

- the embodiment shown on Figure 30 has a socket member 3 including a pair of coaxial recesses 16, and a base member 4 provided with a pair of coaxial arts coaxial protruding extensions 14 arranged to engage with a respective recess 16 in the socket member.

The fact of providing sealing means at the outer surface and sealing means at the inner surface of a connecting group between the socket member and the base member, makes it possible to sanitize the connecting group, i. e. to prevent fluid from stagnate on the surfaces contacted by it.

Clearly, the solution put forward by DE-20 2007008473 U1 does not aim at improving the "cleanliness" and "sanitation" of the filtering unit. Moreover, the gasket of DE-20 2007008473 U1 ensures sealing of the filtering unit from the external environment, whereas the sealing means according to the present invention ensure perfect hydraulic sealing between spaces receiving filtered fluid and spaces for fluid to be filtered. The connecting group and filtering unit described above are susceptible to numerous modifications and variations within the protection scope defined by the contents of the claims.

Claims

1. A connecting group for a filtering unit (2) for filtering a fluid, comprising an annular socket member (3) integral with, or connectable to said filtering unit (2), and delimiting an inner through passage (1 1 ), a base member (4) formed with a through opening (13) in fluid communication, in use, with said through passage (1 1 ), and sealing means (7, 8; 7a; 70, 80) between said socket member (3) and said base member (4),

said socket member (3) and said base member (4) delimiting, in use, an inner surface (5) designed to enter in contact either with a filtered fluid or a fluid to be filtered by said filtering unit (2), and an outer surface (6) designed to enter in contact with fluid to be filtered, or filtered fluid, respectively, by said filtering unit

(2) ,

characterized in that said sealing means has a first part or component (7, 7a, 70) designed to seal said connecting group at said outer surface (6) and a second part or component (8, 7a, 80) designed to seal said connecting group at said inner surface (5).

2. A connecting group as claimed in claim 1 , characterized in that

said socket member (3) has frontal engaging means (14; 16; 24, 25; 26, 27) arranged outside and about said through passage (1 1 ) and designed to face, in use, said base member (4), and

said base member (4) has counter-engaging means (14; 16; 24, 25; 26, 27) arranged outside and about said through opening (13) and designed to engage with said frontal engaging means (14; 16: 24, 25; 26, 27) of said socket member

(3) .

3. A connecting group as claimed in claim 1 or 2, characterized in that said engaging means and counter-engaging means are designed to removably engage with one another.

4. A connecting group as claimed in any previous claim, characterized in that said engaging means extends from a surface (3a) or are formed in a surface (3a) of said socket member (3) contacting, in use, a substantially flat surface (4a) of said base member (4), whereas said counter-engaging means extends from or are formed in said substantially flat surface (4a) of said plate-like member (4) designed to abut against said socket member (3).

5. A connecting group as claimed in any claim 1 to 4, characterized in that said engaging means comprises at least one frontal recess (16) formed in said socket member (3) and locating at least one lug member (17), and said counter- engaging means comprises at least one protruding or projection extension or member (14) extending from said base member (4) and formed with at least one receiving seat (15a) for engagement with a respective lug member (17).

6. A connecting group as claimed in any previous claim, characterized in that said engaging means comprises at least one protruding or projection extension or member (14) extending from said socket member (3) and formed with at least one receiving seat (15a), and said counter-engaging means comprises at least one recess (16) locating at least one lug member (17) for engagement with a respective receiving seat (15a).

7. A connecting group as claimed in any previous claim, characterized in that said socket member (3) has engaging means (14; 16; 24, 25; 26, 27), whereas said base member (4) has counter-engaging means (14; 16; 24, 25; 26, 27) designed to engage with said engaging means (14; 16: 24, 25; 26, 27) of said socket member (3), said sealing means being designed to seal, in use, said engaging means (14; 16; 24, 25; 26, 27) and said counter-engaging means (14; 16; 24, 25; 26, 27).

8. A connecting group as claimed in any previous claim, characterized in that said engaging and counter-engaging means are of the bayonet or threaded or snap-fitting or magnetic type.

9. A connecting group as claimed in any previous claim, characterized in that said through opening (13) in said base member (4) is coaxial and has the same size as said through passage (1 1 ) in said socket member (3).

10. A connecting group as claimed in claim 5 or 6, characterized in that said sealing means comprises at least one gasket member (7a) designed to separate, in use, said socket member (3) from said base member (4) and delimiting at least one through opening (7b) for said at least one protruding member (14).

1 1 . A connecting group as claimed in claim 10, characterized in that said at least one gasket member (7a) is co-extensive and coaxial with said socket member (3).

12. A connecting group as claimed in any previous claim when depending upon claim 5 or 6, characterized in that at least one protruding member (14) is integral with, or secured to, either the socket member (3) or the base member (4).

13. A connecting group as claimed in any previous claim when depending upon claim 5 or 6, characterized in that said at least one protruding member (14) is a ring so shaped as to enclose said passage (1 1 ) or said opening (13) formed in the respective socket or base member and being substantially coaxial therewith.

14. A connecting group as claimed in any previous claim, characterized in that said first part or component (7, 7a, 70) and said second part or component (8, 7a, 80) of said sealing means comprises each at least one respective gasket member (7, 8) located in a respective seat (9, 10) formed either in said socket member (3) or in said base member (4), or formed partly in said socket member (3) and partly in said base member (4).

15. A connecting group as claimed in claim 14, characterized in that said seats (9, 10) are formed either at the edge of said socket member (3) designed to abut, in use, against said base member (4), or at the edge of said through opening (13) in said base member (4) abutting, in use, against said socket element (3).

16. A connecting group as claimed in any previous claim, characterized in that it comprises at least one protective layers (28a, 28b) covering surfaces of said base member (4) designed to contact said fluid.

17. A connecting group (1 ) when provided with a filtering unit (2) secured or integral with said socket member (3).

18. A connecting group as claimed in claim 17, characterized in that said filtering unit (2) delimits an internal space (22) in fluid communication with said through opening (13) delimited by said base member (4).